Originally a rector was a priest who held the living and received all the income from a church - fees for marriages, baptism, funerals and other moneys. If he chose he could install a vicar and pay him. "Vicar" in this context means "stand-in". A priest could hold many livings, and install a vicar in each parish, so he could become very rich indeed, without ever celebrating a single service if that suited him. That is one of the reasons the Church/es fell into disrepute.
If you knew a priest was a rector, you would address him as Rector. Otherwise, as Vicar.
I can't help you with methodists, etc, but "Minister" probably sounds about right.